Diazo-type multicolor reproduction process

ABSTRACT

A process for the diazo-type multicolor reproduction which comprises (A) exposing to light a diazo-type photosensitive material having a photosensitive layer containing at least one diazonium salt (c) and a coupler (b) having a substantially lower rate of coupling with the diazonium salt (c) than that of resorcin, said coupler being present in the photosensitive material in an amount of not greater than 1 mole per mole of said diazonium salt (c), and (B) heating a layer of at least one thermovolatile or thermosublimative coupler (a) disposed in a face-to-face contact with said photosensitive material at a predetermined portion, said steps being carried out coincidentally or in the order of (A) to (B) or (B) to (A), and then developing the exposed photosensitivematerial. photosensitive material.

N ihyakumen et al.

[451 Apr. 4, 1972 [54] DIAZO-TYPE MULTICOLOR REPRODUCTION PROCESS [72] Inventors: Kouzi Nihyakumen, I-Iirakata; Taizo Yokoyama, Osaka; Yasuo Ueda, Kobe; Yasutoki Kamezawa; Tatsuo Aizawa, both of Osaka, all of Japan [73] Assignee: Mita Industrial Company, Ltd., Osaka,

' Japan [22] Filed: July 31,1970

[21] Appl. No.: 59,923

[30] Foreign Application Priority Data Aug. 2, 1969 Japan ..44/60756 [52] US. Cl ..96/49, 96/91, 117/368, 117/369, 250/65 T [51] Int.Cl ..G03c 5/18 [58] Field of Search ..96/49.75, 91; 117/36.7, 36.8, 117/369; 250/65 T [56] References Cited UNITED STATES PATENTS 2,541,178 2/1951 Slifkin ..96/91 X 2,789,904 4/1957 Benbrook et a1 ..96/91 X 3,224,878 12/1965 Klimkowski et al. .....96/49 3,454,764 7/1969 Collier et al. ..96/49 ORIGINAL FOREIGN PATENTS OR APPLICATIONS 1,000,151 8/1965 Great Britain ..96/49 OTHER PUBLICATIONS Landau, R. et al., J. of Photo. Sci., Vol. 13, 5/1965, p. 444- 451 Dinaburg, M. S., Photosensitive Diazo Cpds., 1964, The Focal Press, p. 50 54.

Van der Grinter, The Photographic Journal, 1952, Vol. 928, p. 43- 48.

Primary Examiner-Charles L. Bowers, Jr. Attorney-Sherman and Shalloway 5 ABSTRACT A process for the diazo-type multicolor reproduction which comprises (A) exposing to light a dliazo-type photosensitive material having a photosensitive layer containing at least one diazonium salt (0) and a coupler (b) having a substantially lower rate of coupling with the diazonium salt (0) than that of resorcin, said coupler being present in the photosensitive material in an amount of not greater than 1 mole per mole of said diazonium salt (c), and (B) heating a layer of at least one thermovolatile or thermosublimative coupler (a) disposed in a face-to-face contact with said photosensitive material at a predetermined portion, said steps being carried out coincidentally or in the order of(A) to (B) or (B) to (A), and then developing the exposed photosensitivematerial. photosensitive material.

5 Claims, 3 Drawing Figures 20 NON-565.3)

Patented A ril 4, 1912 3,653,903

I 2 Sheets-Sheet 1 F/g/ Fig 2 I 2 3 2 3 iiiORlGlNAL- fii j ORIGINAL PREPARATION OF ORIGINAL FOR MULTICOLOR DEVELOPMENT #1110 all a COUPLER 2 3 TRANSFERRING 2' 3 COUPLER HEAT SOURCE LI SOURCE LIGHT souRcE I HEAT SOURCE g LIGHT EXPOSURE I I 2' 3' PHOTOSENSITIVE HEAT TRANsFER\ LAYER r I BASE DEVELOPMENT II I2 I3 II I2 I Cit'fi jBASE ciig DIAZO-TYIPIE MULTICOLOR REPRODUCTION PROCESS This invention relates to a process for the diazo-type multicolor reproduction and photosensitive materials in use for said process. More specifically, it relates to a process for the diazo-type multicolor reproduction by which portions of a photosensitive paper corresponding to predetermined portions of the original can be colored selectively to different hues without substantial mingling of colors, and to photosensitive materials in use for said process.

We previously proposed a process for the diazo-type multicolor reproduction based on the discovery that predetermined portions of an original can be reproduced into different hues regardless of difference or similarity of the light transmission in the original by conducting the steps of (A) exposing to light a diazo-type photosensitive material containing at least one diazonium salt (c) and (B) heating a layer of at least one thermovolatile or thermosublimative coupler (a) disposed in a face-to-face contact with a predetermined portion of said diazo-type photosensitive material, said steps being carried out coincidentally or in an order of (A) to (B) or (B) to (A), and then developing the exposed photosensitive material in the presence of a coupler (b) having a lower coupling rate under developing conditions than said thermovolatile or thermosublimative coupler (a).

In case the above process is conducted by employing a com mercially available, diazo-type, two-component photosensitive material, at portions corresponding to predetermined portions of an original there can be formed an azo dyestuff having a different hue from that of a dyestuff formed at other portions, but it has been found that at said portions corresponding to the predetermined portions of the original there is also formed the dyestuff of the same kind as that formed at other portions and mingling of colors is caused to occur, which renders the color contrast indistinct. We have traced the origin of this undesirable phenomenon and found that since conventional diazo-type, two-component photosensitive materials contain a great excess of a coupler, for instance, in an amount of4 moles per mole of the diazonium salt, this coupler (b) couples with the diazonium salt in competition with the thermovolatile or thermosublimative coupler (a), which results in undesired mingling of colors.

We furthered our research and now found that in the abovementioned diazo-type multicolor reproduction process predetermined portions of the resulting copy can be colored selectively in different hues from other portions without substantial mingling of colors by choosing as coupler (b) a coupler having a substantially lower rate of coupling with a diazonium salt (c) of the photosensitive layer than that of resorcin and making said coupler present in the photosensitive layer in an amount of not greater than 1 mole per mole of the diazonium salt.

Thus, in accordance with this invention, there is provided a process for the diazo-type multicolor reproduction which comprises conducting the steps of (A) exposing to light a diazo-type photosensitive material having a photosensitive layer containing at least one diazonium salt and a coupler (b) having a substantially lower rate of coupling with the diazonium salt (c) than that of resorcinol, said coupler (b) being present in the photosensitive material in an amount of not greater than 1 mole per mole of said diazonium salt (c), and (B) heating a layer of at least one thermovolatile or thermosublimative coupler (a) disposed in a face-to-face contact with said photosensitive material at a predetermined portion, said steps being carried out coincidentally or in an order of (A) to (B) or (B) to (A), and then developing the exposed photosensitive material.

Any coupler that has a substantially lower rate of coupling with a diazonium salt (c) contained in a photosensitive material than that of resorcinol, preferably that of 2,3-dihydroxynaphthalene, can be used as coupler (b) in the process of this invention. Typical examples of such coupler (b) are as follows Phenol Derivatives 2,5 ,6-Trimethylphenol 2-ll-lydroxymethylphenol B-( Z-Hydroxyphenyl)-propionic acid Z-(w-Phenylaminomethyl )-phenol B-(4-Methyl-2-hydroxyphenyl)-glutaric acid 2,5-Dimethyl-6-(N-dimethylaminomethyl)-phenol 1,3-Dimethyl ether of pyrogallol a-Resorcylic acid ethanolamine ,BResorcylic acid N-Lauryl-p-aminophenol N-Acyl-m-aminophenol Meta-hydroxy-acetoanilide Ortho-N-hydroxyphenyl-monoguanidine Para-N-hydroxyphenyl-biguanidine 2,5-Dimethyl-4-morpholinomethyl phenol 2-Methyl-5-isopropyl-morpholinomethyl phenol 4-Morpholinomethylresorcinol monomethyl ether 3 ,3,5-Trihydroxydiphenyl 3 ,3,5,5-Tetrahydroxydiphenyl 2,2 ,4,4'-Tetrahydroxydiphenyl 2,4,4'-Trihydroxydiphenyl-2'-sulfonic acid 2,4,6,3,5-Pentahydroxydiphenyl 2,2 ,4,4'-Tetrahydroxydiphenyl sulfide 3-(Aminophenylsulfonylamine) phenol l,3-Dihydroxy-S-chlorobenzene 4-Bromoresorcinol 4-Iodoresorcinol 4-Fluororesorcinol N-B-Hydroxyethyl-2-resorcylamide a-Resorcylamide N-Phenyl-a-resorcylamide l,3-Dihydroxybenzene-S-sulfonic acid 3,5-Dihydroxytoluene 1,3,5-Resorcylic acid ethanolamine 1,2,5-Resorcylic acid ethanolamine 1,3,5-Resorcylic acid anilide 1,3,5-Resorcylic acid amide 4-Choloro-3,S-dihydroxybenzoic acid amide 3,5-Dihydroxybenzoic acid amide m,m'-Trimethylenedioxy diphenyl m,m'-l-Methyltrimethylenedioxy diphenyl 6,6-Dimethyl-3,3-trimethylenedioxy diphenyl m,m-(p-Phenylene-dimethylenedioxy)-diphenyl 6,6-Dihexyl-3,3-isopropylenedioxy diphenyl Resorcinol acetaldehyde Resorcinol-phosgen reaction product Bis-(2,4-diphenylsulfide) Bis-(2,4-diphenylsulfoxide) Phloroglucinol 1,3 ,5-Trihydroxy-Z-methylbenzene F luoroglycinol monoethyl ether 3,3,S'-Trihydroxydiphenyl 2,4,4'-Trihydroxydiphenyl 3,3',5,5 -Tetrahydroxydiphenyl 4,4 ,6,6-Tetrahydroxydiphenyl Phloroglycide Naphthols 2,3-Dihydroxynaphthalene-6-sulfonic acid 2-Naphtho1-3,6-disulfonic acid 2,7-Dihydroxynaphthalene-3-sulfonic acid 2,8-Dihydroxynaphthalene-fi-sulfonic acid 1 ,B-Dihydroxynaphthalene-8-sulfonic acid l-8-Aminonaphthol-5-sulfonic acid 2,7-Dihydroxy-3,o-disulfonic acid 1,8-Benzoylaminonaphthol-2-sulfonic acid 1 ,8-Dihydroxynaphthalene-6-sulfonic acida 2-Hydroxy-3-naphthionic-N-fi-hydroxyethyl amide B-Hydroxynaphthionic acid aminoethylamine 2-Hydroxy-3-naphthionic-N,N-bis-[3-hydroxyl ether amide 8-l-lydroxy-2-naphthionic-hydroxyethyl amide 1-( N-Carboethoxymethylamino )-8-naphthol-4-sulfonic acid 5-(Para-nitro)-benzamido-l-naphthol l-Hydroxynaphthyl-7-phenyl-guanidine 2-l-lydroxynaphthyl-8-biguanidine l-Naphthol-3-(N-B-hydroxyethyl)-sulfonic amide l-Naphthol-3-(N-o-methoxyphenyl)-sulfonic amide Bis-[ 5-hydroxy-7-sulfo-naphthyl( 2 ]-amine N,N-Bis[1hydroXy-3-sulfo-naphthyl(6)]-thiourea 2,3-Dihydroxynaphthalene 2,7-Dihydroxynaphthalene 2,8-Dihydroxynaphthalene-3,fi-disulfonic acid 2,7-Dihydroxy-1-naphthalene-methanesulfonic acid l,5-Dihydroxynaphthalene l,6-Dihydroxynaphthalene-3sulfonic acid l,8-Dihydroxynaphthalene-3sulfonic acid lHydroxy-8-aminonaphthalene-6-sulfonic acid I ,8-Diaminonaphthalene-4-sulfonic acid 2,7Dihydroxynaphthalene-6-sulfonic acid Active Methylene Group-containing Compounds Acctoacetic acid cyclohexylamide Acetoacetic acid benzylamide Cyanoacetoanilide Cyanoacetomorpholine 2,4-Diacetoacetoaminotoluene Diacetoacetyl piperidine Heterocyclic Compounds 1-( 3 -Sulfoamide )-phenyl-3 methylpyrazolone-S l-(4Carboxy-ethylphenyl)-3-dodecyl-pyrazolone-5 8-Hydroxy-l ,2-naphthylimidazole 2-Methyl-4-hydroxybenzimidazole 7-Methyl-4-hydroxybenzothiazole l,7-Dimethyl-4-hydroxy-benzotriazole 3-Hydroxythiophene-5-carboxylic acid l-3-4-Cyclopentatrione Compounds Expressed by the Following General Formula wherein X stands for =0, =S or =NZ Z stands for Z or a group Z stands for an arylene group; 2 and 2 each are selected from hydroxyaryl groups; and 2;; stands for hydrogen, or an alkyl group or an hydroxyalkyl or hydroxyaryl group which may have another substituent than the hydroxyl group.

N,N,N"-Tris-[ lhydroxy-3-sulfonaphthyl(6)]guanidine N-[ lHydroxy-8-naphthyl]-N,N'-bis[ l-hydroxynaphthyl(6)]guanidine N-2-Hydroxyethyl-N',N"-bis-[ l-hydroxy-3-sulfonaphthyl(6)]guanidine N,N-Bis[ lhydroxy-3-sulfonaphthyl(6)]guanidine N,N-Bis[ l-hydrxy-8-sulfonaphthyl(6)]urea N,N',N"-Tris[ ll-hydroxyphenyl(3 ]guanidine 4,4-Bis{N,N"-[1-hydroxyphenyl(3)]quanidine}diphenyl 4,4'-Bis {N,N' 1hydroxy-3-sulfonaphthyl( 6)] quanidine} diphenyl Compounds Expressed by the Following General Formula wherein A and A stand for an aromatic ring which may have optional substituents other than the hydroxyl and primary amino groups. Bis-[hydroxy-7-sulf0naphthyl(2)]-amine Bis-[8-hydroxy-2,4-disulfonaphthyl( l )]-amine Bis-[ 8hydroxy-6-sulfonaphthyl( 2 ]-amine Bis-[ 8hydroxy-4-sulfonaphthyl( 1 )]-amine Diazo Compounds Capable of Forming Bis-azo Compounds NPQAGMQAQ in which X is m ulkyl. ulkoxy or acyl group.

In this invention any of the above-cited compounds listed on pages 4-9 may be used as coupler (b), but it is preferable to employ couplers having two or more hydroxyl or active methylene groups and being capable of forming polyazo dyes such as bis-azo dyes and tris-azo dyes, especially couplers having two or more aromatic rings containing a hydroxyl group.

In case a coupler capable of forming a bis-azo or poly-azo dye is used, it is desired to make the coupler present in the photosensitive material in an amount of 0.5 0.1 mole per mole of the diazonium salt (0).

"H030 nun In case a coupler capable of forming a bis-azo or poly-azo dye is used in combination with a coupler forming a mono-azo dye, the coupler for a bis-azo or poly-azo dye is used in an amount of 0.5 0.1 mole per mole of the diazonium salt and the coupler for a mono-azo dye is used in an amount of 0.9 0.1 mole per mole of the diazonium salt, with the proviso that the total amount of both couplers is within the range of 0.9 0.1 mole per mole of the diazonium salt.

Any of conventional photo-resoluble diazonium salts used as diazo-type photosensitive materials may be used as diazonium salt (c) in this invention, so far as it is capable of coupling with the above-mentioned coupler (b) under ordinary developing conditions. Examples of such diazonium salt are as follows:

OPara-phenylene-diamine-N,N-substituted compounds of the following general formula:

wherein X stands for an anion, R and R" each are aliphatic groups, and Z and Y denote groups which can be introduced into the benzene nucleus. Specific examples of the compounds of this type are as follows:

4-Diazo-N,N-dimethyl aniline (referred to simply as MA salt") 4-Diazo-N,N-diethyl aniline (referred to simply as EA salt) 4-Diazo-N-ethyl-N-B-hydroxyethyl aniline (referred to simply as EH salt) 4-Diazo-N,N-bis-[B-hydroxyethyl aniline 4-Diazo-N-methyl-N-B-hydroxyethyl aniline 4-Diazo-N-ethyl-N-B-hydroxypropyl aniline Other diazonium salts of p-phenylene diamines N,N- substituted with alkyl or hydroxy-alkyl groups 4-Diazo-N-ethyl-N-(B-diethylamino)-ethyl aniline 4-Diazo-2-chloro-N,N-diethyl aniline 4-Diazo-2-methyl- N,N-diethyl aniline 4-Diazo-2-iodo-N,N-diethyl aniline 4-Diazo-2-trifluoromethyLN,N-diethyl aniline 4-Diazo-N-ethyl-N-benzyl aniline 4-Diazo-N-methyl-N-benzyl aniline (referred to simply as methyl benzyl) OAminohydroquinone ether-type compounds of the following general formula:

wherein R, R and R" are alkyl or aryl groups and X stands for an anion.

Specific examples of the compounds of the above type are as follows:

4-Diazo-2,5-dibutoxy-N,N-diethyl aniline 4-Diazo-2,S-diethoxy-N-benzoyl aniline (referred to simply as BB salt) 4-Diazo-2,5-diethoxy-N-ethyl-N-benzoyl aniline 4-Diazo-2,S-dibenzyloxy-N-benzoyl aniline 4-Diazo-2-chloro-5-methoxy-N-benzoyl aniline 4-Diazo-2,5-diethoxy-N-benzoyl-methyl aniline 4-Diazo-2,5-diethoxy-N-benzoyloxy-metl'iyl aniline Other 4-diazo-2,5-dioxyalkyl (or dioxyaryl)-N- alkyl (or aryl) compounds and derivatives thereof Aminodiphenyl compounds, aminodiphenyl amine compounds and their analogues of the following general formulas:

wherein X is an anion, R is a divalent aryl group,

R is a monovalent or divalent aryl or alkyl group,

A is a divalent group or a direct bond and examples of the R-A-R' are diarylamine (A; -NIH-), diphenyl (A; direct bond), diphenyl oxide (A; -O-), diaryl methane (A; -Cl-l stilbene (A; -CH CH-) and diaryl or dialkyl sulfide (A; -S-) Specific examples of the compounds. of the above type are as follows:

Para'diazophenyl amine 4-Diazo-2,5,4'-triethoxydiphenyl amine 4-Diazo-2,5,4,'-triethoxydiphenyl 4,4-Bis-diazo-2,2,5,5-tetrahydroxydiphenyl methane Bis-diazo-8,8'-dichloro-5,5 -dimethoxy benzidine 4-Diazo-2,S-dimethoxyphenylethyl sulfide 4-Diazo-2,5-diethoxy-4-methyl-diphenyl sulfide O Heterocyclic amine derivatives of the following general Y ourcm wherein X stands for an anion, Y and Z are groups which can be introduced into the benzene nucleus,

and A is a direct bond or a divalent group such as -O-, -S- and methylene.

Specific examples of the compounds of this type are as follows:

4-Diazo-2,5-dibutoxy-N-phenyl morpholine 4-Diazo-2,5-diethoxy-N-phenyl morpholine 4-Diazo-2methoxy-N-thio morpholine 4-Diazo-N-phenyl piperidine 4-Diazo-N-phenyl pyrrolidine 4-Diazo-2,5-di-n-butoxy-N-phenyl piperidine Other derivatives of 4-Diazo-N-phenyl heterocyclic amines.

CNN-Substituted ortho-phenylene'diamine derivatives and orthoamino-phenol derivatives.

Specific examples of the compounds of this type are as follows:

2Diazo-4-methylmercapto'N,N'-dimethyl aniline 2-Diazo-5-benzoylamino-N,N"dimethyl aniline 2-Diazol naphthol-S-sulfonic acid The above-mentioned diazonium compounds may be used in the form of a relatively stable salt with sulfuric acid or hydrochloric acid. They may be also used in the form of a double salt with zinc chloride, tin chloride, aluminum sulfate or the like. Further, they may be used in the state stabilized by an aryl sulfonate (in the form of a diazonium salt of an aromatic sulfonic acid), a diazosulfonate or the like. These diazonium salts may be used either singly or in the form of a mixture of two or more of them.

In accordance with this invention, the above-mentioned coupler (b) is used in an amount of not greater than 1 mole per mole of such diazonium salt (0). In case the amount of the coupler (b) is more than 1 mole per mole of the diazonium salt (c), when the coupling reaction is allowed to advance between the diazonium salt (0) and the coupler (a) heat-transferred on the photosensitive layer, the coupling reaction between the diazonium salt (c) and the coupler (b) is also allowed to advance to some extent, which sometimes results in occurrence of undesired mingling of colors. However, if the amount of the coupler (c) in the photosensitive layer is made less than 1 mole per mole of the diazonium salt, it is possible to form a dyestuff composed of the coupler (a) and the diazonium salt (c) selectively at portions of the photosensitive layer corresponding to predetermined portions of the original. In this sensitizing composition for dry development:

Diazo compound (c) Azo coupling component (b) 0.2-0.9 mole per mole of diazo com pound (c) Organic acid 0.1-5.0 71 Coloring matter (ION-0.025 7: Development promoter l.0-l0.0 7r Extender 2.5 Solvent balance The sensitizing composition of the above recipe is coated on a substrate such as paper and plastic film, and dried to form a photosensitive sheet.

Two-component-type sensitizing composition for wet development:

Diazo compound (c) Azo coupling component (b) 0.2-09 mole per mole of diazo compound (c) Organic acid 0. l-5.() 71 Extender ()2.5 7:

Stabilizer O-5.0 7: Coloring matter 0.00l-0.025 7r Solvent balance The sensitizing composition of the above recipe is coated on a substrate such as paper and plastic film, and dried to form a photosensitive sheet.

As the organic acid in the sensitizing composition there may be used citric acid, tartaric acid, oxalic acid, sulfamic acid, etc. As the extender there may be used dextrin, gum arabic, colloidal silica, etc. As the stabilizes there may be used 1,3,6- naphthalene, sodium trisulfonate and other aryl sulfonic acids. Polyhydric alcohols such as glycerin and ethylene glycol are used as development promoter. Coloring matters are used for indicating the photosensitive face and increasing the whiteness of the back ground, and blue dyestuffs such as methylene blue and Patent Blue are used for this purpose. As the solvent there may be used water and organic solvent such as alcohols, acetone, toluene, xylene and esters.

The multicolor reproduction using the diazo-type photosensitive materials of this invention is performed by conducting the steps of (A) exposing to light a photosensitive material containing at least one diazonium salt (c) and a coupler (b) in the above-mentioned amount and (B) heating a layer of at least one thermovolatile or thermosublimative coupler (a) disposed in a face-to-face contact with said photosensitive material at a predetermined portion, said steps being carried out coincidentally or in an order of (A) to (B) or (B) to (A), and then subjecting the exposed photosensitive material under developing conditions.

It is essential that among thermovolatile or thermosublimative coupler (a), coupler (b) and diazonium salt (0) to be used in this invention there should be established the following relations:

1. Thermovolatile or thermosublimative coupler (a) has a higher coupling rate under developing conditions than coupler II. Dyestuff (b)-(c), dyestuff (a)(c), dyestuff (a)- (c) ..formed at the development have hues different to one another.

Any coupler that can be volatilized or sublimated under heating conditions may be used as thermovolatile or thermosublimative coupler (a) in this invention. As such coupler (a) there may be mentioned phenol derivatives. hydroxynaphthalene derivatives, aniline derivatives and active methylene group-containing compounds. In view of facilitation of the heat transfer operation it is preferred that these derivatives do not contain soluble groups such as a sulfonic acid group.

Examples of these derivatives usable as coupler (a) are as follows:

Phenol Derivatives Phenol Pyrocatechol Resorcinol Phloroglucinol o-Hydroxybenzalcohol Resorcinol monoglycol ether Resorcinol diglycol ether Hydrotoluquinone Pyrogallol-4-carboxylic acid Vanillin lsovanillic acid Vanillic acid S-Hydroxy-isophthalic acid 2-l-lydroxy-terephthalic acid 2Hydroxy-p-toluylic acid 3-Hydroxy-p-toluylic acid S-Hydroxy-o-toluylic acid -l-lydroxy-m-toluylic acid S-Hydroxy-l-naphthonic acid Para-hydroxyphenylacetic acid 2,7-Dihydroxynaphthalene 2,3-Dihydroxynaphthalene 8-Amino-2-naphthol 2,2-dihydroxyl l -binaphthyl 4,4-dihydroxyl 1 -binaphthyl 3-carboxy-2-naphthol Aniline Derivatives Meta-aminobenzoic acid Z-Amino-p-cresol Ortho-aminophenol Para-aminophenol Para-chloroaniline 3,4-Diaminotoluene Active Methylene Group-containing Compounds l-Phenyl-3-methylpyrazolone (5) l-Phenyl-3-carboxypyrazolone Acetoacetic acid anilide Acetoacetic-o-chloroanilide Para-hydroxybenzaldehyde Ortho-hydroxybenzoic acid Ortho-hydroxybenzyl alcohol 4,4-Dihydroxybiphenol 3,5-Dichloro-salicylic acid 5-Chloro-2-nitrophenol 2,5-Dihydroxyacetophenone 2,5-Dinitrophenol 2,4-Dinitrophenol 2,4-Dinitroresorcin 4,6-Dibromo-2-nitrophenol 2,5-Dimethyl hydroquinone Hydroxynaphthalene Derivatives 2,3-Dihydroxynaphthalene B-Naphthol a-Naphthol l ,fi-Dihydroxynaphthalene 2,6-Dihydroxynaphthalene 2,7-Dihydroxynaphthalene In case a plurality of thermovolatile or thermosublimative couplers (a) are used, the coupling rate of the coupler (b) should be lower than that of any of couplers (a). Selection of couplers (a) and (b) meeting the above requirement may be easily performed by those skilled in the art based on a simple experiment.

In conducting the reproduction process of this invention, at first an original for multicolor development is formed by applying at least one transparent or semi-transparent layer of a thermovolatile or thermosublimative coupler (a) onto the back surface of one or more predetermined portions of a transparent or semi-transparent original to be copied.

The so formed original for multicolor development is overlapped on a diazo-type photosensitive material containing at least one diazonium salt (c) and a coupler (b) in a manner such that the layer of coupler (a) will confront the photosensitive surface of the photosensitive material, and the light-exposure and heating are effected coincidentally with the above overlapping or after the said overlapping. Thus, the thermovolatile or thermosublimative coupler (a) is heat-transferred to the surface of the predetermined portion of the photosensitive material, and the light resolution of the diazonium salt (c) in the photosensitive material is caused to occur depending on the light transmission of the original. When the so exposed photosensitive material is developed by a method known per se, at the predetermined portion to which the coupler (a) has been heat-transferred, the diazonium salt (c) at the non-exposed area reacts selectively and preferentially with the coupler (a) to form a dyestuff (c) (a) and at other portion the diazonium salt (c) at the non-exposed reacts with coupler (b) to form a dyestuff (c) (b). Thus, there is obtained a multicolored reproductive copy in which the predetermined portion is colored in a hue different from that of the other portion.

The above-mentioned original for multicolor development may be prepared, for instance, by a method comprising applying a coating composition containing the above-mentioned thermovolatile or thermosublimative coupler (a) onto the back surface of a portion predetermined to have a different hue, of a transparent or semi-transparent original to be copied, or by a method comprising coating or impregnating a transparent or semi-transparent substrate with the said coating composition and combining the resulting sheet for heat-transferring the coupler, with the back surface of the specific portion of the original predetermined to have a different hue in a manner such that the layer for heat-transferring the coupler will confront the photosensitive material.

A coating composition for treating the back surface of an original and forming a layer for heat-transferring the coupler can be easily prepared by dispersing a coupler (a) into a liquid, semi-solid or solid dispersion medium.

Such treating agent will be now described by referring to some embodiments.

l. Ink-like composition for treating the back surface of an original:

Coupler (a) 5.0-25.0 7: Coloring material 0- 3.0 7k Binder 0- 5.0 Dispersion assistant 0- 2.0 7: Dispersion medium balance As the dispersion medium there may be used water and organic solvents such as alcohol, toluene, xylene, esters and methyl ethyl ketone. It is possible to incorporate a coloring material so as to confirm the formation of a film of the treating agent, or to use a binder for the purpose of obtaining a good fixation of the coupler.

The composition of the above recipe is applied to the back surface of a portion predetermined to have a different hue by means of a brush, an installed felt pen, a ball pen, a coating roller, a sprayer or a printing machine.

2. Waxy composition for treating the back surface of an original:

Coupler (a) 5.0-25.0 7c Wax 85.0-15.0 Oil 10.0-40.0 7: Coloring material 020.0 k

The composition of the above recipe is shaped to have a crayon stick-like form or a chalk-like form, and the back surface of a portion of an original predetermined to have a different hue is painted therewith. It is also possible to form a pressure-sensitive transfer sheet by melting the above composition or dissolving it in a suitable solvent and coating the melt or solution on a substrate such as paper and plastic film. The so formed pressure-sensitive transfer sheet is overlapped on the back surface of an original sheet, and then pressing is effected thereon by means of a typewriter or other writing means to form a heat-transferable layer on the back surface of an image predetermined to have a different hue.

3. Coupler-transferring sheet for treating the back surface of an original:

The ink-like composition for treating the back surface of an original, which was described in (l), or a composition obtained by incorporating a binder or an extender into such inklike composition is coated on a transparent or semi-transparent sheet such as paper, plastic film or non-woven fabric. The so formed sheet for heat-transferring the coupler is cut into a desired size, if necessary, and then applied to the back surface of a portion of an original determined to have a different hue. It is possible to form a pressure-sensitive adhesive layer on the back surface of the coupler-transferring layer for preventing it from exfoliating from the original.

The so prepared original for multicolor development may be generally used 5 to times repeatedly for the multi-color development, though the applicable frequency of the repeated use varies depending on the amount coated of coupler (a), the coating method, the heating method and the developing method. Of course, when the heat-transferability of coupler (a) in the layer for heat-transferring the coupler is lowered, it is sufficient to supply newly an additional layer for heattransferring the coupler.

The exposure of the photosensitive material and the transfer of the thermovolatile or thermosublimative coupler (a) to the photosensitive surface may be effected coincidentally. For instance, in case a mercury lamp is used as light source for expo sure, the heat transfer of the coupler (a) may be effected coin' cidentally with the exposure by the heat conveyed through a cylinder glass of the light source maintained at a relatively high temperature. Of course, the heat "transfer of the coupler (a) may be also effected by the radiation heating of an image of the original. The heat transfer of the coupler (a) may be effectively performed by heating the layer for heat-transferring the coupler at a temperature above 50 C., preferably above 70 C., though a preferable heating temperature varies to some extent depending on the kind of the coupler (a) and the heating time. It is also possible to adopt a method comprising placing the above-mentioned original for multicolor development and the photosensitive material, passing the assembly through a heated roller or an infrared radiation zone to heat the layer for heat-transferring the coupler at the above-mentioned temperature and to effect the heat transfer of the coupler, and then passing the same through an exposure zone to effect the exposure of the photosensitive material.

It is also possible to adopt a method in which the exposure and heat transfer are conducted in an order reverse to that of the above method, namely a method comprising placing the original for multicolor development and the photosensitive material, passing the assembly through an exposure zone to effect the exposure of the photosensitive material and then passing the same through a heating zone to effect the heat transfer of the coupler (a).

In accordance with this invention, the photosensitive material which has been exposed to light and on a predetermined portion of which the coupler (a) has been heat-transferred, is developed by means known per se. The development may be conducted by either a dry method or a wet method.

In accordance with the dry process, the development may be performed sufficiently only by exposing the light-exposed photosensitive material to a mixture of ammonia and steam. In the case of the moist process the development can be accomplished by contacting the photosensitive material with an aqueous liquid developer containing an alkali.

In accordance with this invention there can be obtained multicolored reproductive copies in which the portions corresponding to predetermined portions of an original are colored selectively in different hues independently from other portions without any undesired mingling of colors. Further, multi-coloration can be accomplished by conducting the single-step development.

This invention will now be detailed by referring to accompanying drawings.

In the drawings,

FIGS. 1 and 2 are diagrams given to illustrate the multicolor reproduction process of this invention and FIG. 3 is a CIE chromaticity diagram showing the results of Comparative Example in which the molar ratio of the coupler (b) to the diazoniurn salt was varied, which Comparative Example will be detailed hereinbelow.

In the embodiment of this invention illustrated in FIG. 1, different thermovolatile or thermosublimative couplers 2 and 3 are coated on the back surfaces of images 2 and 3, respectively, of an original having images I, 2 and 3. When the so formed original for multicolor development is placed on a photosensitive paper, and exposed to light emitted from a suitable light source, latent images 1", 2" and 3" corresponding to images I, 2 and 3 are formed on the photosensitive layer and couplers 2' and 3' are transferred on the upper surface of the photosensitive layer by the heat from the light source. When this photosensitive sheet is developed, the diazonium salt in latent images 2" and 3" of the photosensitive layer reacts selectively with transferred couplers 2 and 3, while the diazonium salt in latent image 1 reacts with a coupler contained in the photosensitive layer. Thus, there is obtained a reproductive copy which has images 11, 12 and 13 colored in different hues.

FIG. 2 is a view illustrating an embodiment similar to the above embodiment shown in FIG. 1, except that a heat-transferable sheet containing coupler 2 and another heat-transferable sheet containing coupler 3' are applied to the back surfaces of images 2 and 3, respectively.

This invention will be now described by referring to examples.

EXAMPLES OF THE PREPARATION OF INK-LIKE AGENTS FOR TREATING THE BACK SURFACE OF AN ORIGINAL Example A An ink-like composition of the following recipe is prepared as a yellow color-forming agent for treating the back surface of an original:

Acetoacetic anilide 20 g. Glycerin 15 g. Alkyd resin 5 g. Methanol 100 ml.

The above composition is directly used as a material to be coated on the back surface of a portion of the original desired to be reproduced in yellow by means of a brush, a coating roller or a sprayer, or after it has been charged in a felt pen or a ball pen, it is used as a material for treating the back surface of a portion of the original desired to be reproduced in yellow.

Example B An ink-like composition of the following recipe is prepared as a red color-forming agent for treating the back surface of an original:

l-PhenyI-S-methylpyrazolone (5) g. Styrene resin 5 g. Glycerin 15 g. Ethanol I00 ml.

The above composition is directly used as a material to be coated on the back surface of a portion of the original to be reproduced in red by means of a brush, a coating roller or a sprayer, or after it has been charged in a felt pen or a ball pen, it is used as a material for treating the back surface of a portion of the original to be reproduced in red.

Example C An ink-like composition of the following recipe is prepared as a brown color-forming agent for treating the back surface of an original:

Resorcinol 20 g. Vinyl acetate resin 5 g. Glycerin l5 g. Methanol I00 ml EXAMPLES OF THE PREPARATION OF WAXY AGENTS FOR TREATING THE BACK SURFACE OF AN ORIGINAL Example E A waxy composition to be used as a yellow color-forming agent for treating the back surface of an original is prepared by heat melting Acetoacetic anilide 30 g. Stearic acid 100 g. Paraffin 50 g. Terra abla 50 g. Diatomaceous earth 20 g.

and solidifying the melt.

The above composition is molded into a crayon stick-like form and is used as a material to be coated on the back surface ofa portion of the original desired to be reproduced into a different hue.

Example F A waxy composition to be used as a yellowish brown colorforming agent for treating the back surface of an original is prepared by heat melting Resorcinol monoglycol ether 20 g. Paraffin 50 g. Terra abla g. Haze wax 20 g. Stearic acid 100 g. Magnesium carbonate 20 g.

and solidifying the melt.

The so formed composition is molded into a crayon sticklike or chalk-like form and is used as a material for coating the back surface of a portion of an original desired to be reproduced in a different hue.

Example G A waxy composition of the following recipe is prepared as a red color-forming agent for treating the back surface of an original:

l-Phenyl-3-methylpyrazolone (5) 20 g. Stearic acid I00 g. Paraffin 50 g. Diatomaceous earth 30 g. Haze wax 20 g.

The above composition is molded into a crayon stick-like or chalk-like form and is used as a material for coating the back surface of a portion of the original desired to be reproduced in a different hue.

Example I-I inqnan To the composition of Example G are added 100 g. of mineral oil, 50 g. oleic acid and 20 g. of Permanent Red, and the mixture is kneaded in a bowl mill to disperse additional components uniformly. Then, the kneaded mixture is coated on a substrate such as paper to obtain a pressure-sensitive copy sheet. The so formed copy sheet is overlapped on the back surface of an original and the pressing is effected thereon by means of a typewriter or other writing means. Thus, the sheet is used as a material for forming a layer of the waxy agent on the back surface of an image of the original to be reproduced in a different hue.

EXAMPLES OF THE PREPARATION OF COUPLER- TRANSFERRING SHEETS FOR TREATING THE BACK SURFACE OF AN ORIGINAL Example I A composition of the following recipe is prepared as a yellow color forming agent for treating the back surface of an original:

Acetoacetic acid aniline 20 g. Triacetate resin g. Methanol 30 ml.

Acetone 30 ml.

The above composition is coated on a transparent or semitransparent sheet such as polyester film by means of a rod coater and dried at a relatively low temperature (40 50 C.) to form a sheet for heat-transferring the coupler. After being cut into a desired size according to need, the sheet is used as a material to be applied to the back surface of a portion of an original desired to be reproduced in a different hue.

Example J A composition to be used as a red color-forming agent for treating the back surface of an original is prepared by using 1- phenyl-3-methylpyrazolone (5) instead of acetoacetic acid aniline in Example I. From this composition there is formed a sheet for heat-transferring the coupler capable of forming a red color.

Example K A composition to be used as a blue color-forming agent for treating the back surface of an original is prepared by using 2,3-dihydroxynaphthalene instead of acetoacetic acid aniline in Example I. From this composition there is formed a heattransferable sheet capable of forming a blue color.

Example 1 Multicolor-forming diazo'type photosensitive paper in use for dry development A solution of the following recipe is prepared:

4-DiaZQN.Ndimethyl-aniline chloride-H2 ZnCl, 5 g. Diethylene glycol 60 g Citric acid 30 g Z.3-Dihydroxynaphthalene fi sulfonic acid g Zinc chloride 50 g Thiourea Patent Blue 0.1 g Water balance Total l liter The solution is coated on a base paper by a customary coating procedure such as using an air knife coater and dried to form a photosensitive sheet.

The sheet is overlapped on an original in which the back surface of a portion is treated with the treating material prepared in Example A and the back surface of another portion is treated with the treating material prepared in Example B. Then, the assembly is heated at 70 100 C. and exposed to light by means of a mercury lamp to form a latent image of the diazonium salt.

Next, the so treated sheet is subjected to development with gasified ammonia and steam. Thus, there is obtained a clear multicolor copy in which a portion corresponding to the portion treated with the material of Example A is colored in a yellow color, a portion corresponding to the portion treated with the material of Example B is colored in red and other portion corresponding to the untreated portion is colored in blue.

Example 2 When Example 1 is repeated by using 4-diazo-N-ethyl-N- hydroxyethyl-aniline chloride-M2 ZnCl instead of 4diazo- N,N-dimethylaniline chloride-U2 ZnCl there is obtained a multicolor reproductive copy similar to that of Example 1.

Example 3 Multicolor-forming photosensitive paper in use for dry development A solution of the following recipe is prepared:

4-Diazo-N,N'diethylaniline chloride l/2 ZnCl 15 g. Glycerine 50 g. Citric acid 40 g. 2-naphthol-3,fi-disulfonic acid 6 g. Zinc chloride 25 g. Thiourea 25 g. Patent Blue 0.1 g Water balance Total I liter By a customary coating method such as using an air knife coater, a photosensitive paper is prepared from the above solution. The photosensitive paper is placed on an original in which a portion of the back surface is treated with the waxy composition prepared in Example E and another portion of the back surface is treated with the composition prepared in Example G. The assembly is exposed to light and heated by means of a mercury lamp. Then, the so treated sheet is subjected to development with gasified ammonia and steam. Thus, there is obtained a clear three-color reproductive copy in which a portion corresponding to the portion of the original treated with the composition of Example E is colored in yel low, a portion corresponding to the portion treated with the composition of Example G is colored in red, and other portion corresponding to the untreated portion of the original is colored in bluish violet.

Example 4 Multicolor-forming photosensitive paper in use for dry development A solution of the following recipe is prepared:

4-Diazo-N,N-dimethylaniline chloride-l/ZZnCl 20 g Diethylene glycol 50 g Citric acid 50 g 2,7-Dihydroxynaphthalene- 3,6-disulfonic acid sodium salt 8 g. Resorcinol monoethyl ether 2 g. Zinc chloride 10 g. Thiourea 50 g. 1,3 ,6Naphthalenetrisulfonic acid sodium salt 20 g Patent Blue 0.l g Water balance Total 1 liter In the same manner as in Example 1, a photosensitive paper is prepared from the above solution by coating and drying. The photosensitive paper is placed on an original, a portion of the back surface of which is treated with the coupler-heattransferring sheet prepared in Example .I and another portion of the back surface of which is treated with the treating agent obtained in Example K. Then the assembly is heated and printed by means of a mercury lamp, followed by development with gaseous ammonia and steam. Thus there is obtained a clear three-color reproductive copy in which a portion corresponding to the untreated portion of the original is colored in red.

Example 7 Multicolor-forming photosensitive paper for dry developresponding to the portion treated with the treating agent of ment The above solution is coated on a semi-transparent paper such as tracing paper and dried to form a photosensitive paper. The photosensitive paper is placed on an original, a portion of the back surface of which is treated with the inklike composition prepared in Example B and another portion of the back surface of which is treated with the composition obtained in Example D. Then the assembly is heated and printed by means of a mercury lamp, followed by development with gasepus ammonia and steam. Thus there is obtained a clear three-color reproductive copy usable as the intermediate in which a portion corresponding to the portion of the original treated with the composition of Example B is colored in red, another portion corresponding to the portion treated with the composition of Example D is colored in blue and other portion corresponding to the untreated portion of the original is colored in yellowish brown.

Example 6 Multi-color-forming photosensitive paper for dry development A solution of the following recipe is prepared:

4-Diazo-N-ethyl N-hydroxyethylaniline chloride-l/ZZnCl g. Dielhylene glycol 75 g. Tartaric acid 40 g. a-resorcylic acid amine 8 g. Zinc chloride 50 g. Thiourea g. Patent Blue O,l g. Water balance Total l liter By a customary coating method such as using an air knife coater, the above solution is applied to a substarate of a photosensitive paper and dried. The so formed photosensitive paper is placed on an original, a portion of the back surface of which is treated with a coupler-heat-transferring sheet prepared in Example K, and the assembly is heated and printed by means of a mercury lamp, followed by development with gaseous ammonia and steam. Thus there is obtained a clear two-color reproductive copy without any substantial mingling of colors, in which a portion corresponding to the portion of the original treated with the sheet obtained in Example K is colored in blue and the remaining portion cor- A solution of the following recipe is prepared:

4-Diazo-N,N diethylaniline .l/2ZnCl, 20 g Eiethylene glycol 50 g Citric acid 20 g Bis-[5hydroXy-7-sulfonaphthyK2 )1- amine M g Zinc chloride 30 g Thiourea 25 g. Hydrochloric acid (36%) 10 ml. Patent Blue 0.1 g Water balance Total 1 liter The above solution is applied to a photosensitive paper substrate by a customary coating method such as using an air knife coater, and the resulting photosensitive paper is placed on an original, a portion of the back surface of which is treated with the ink-like composition obtained in Example C. The assembly is heated and printed by means of a mercury lamp, followed by development with gaseous ammonia and steam. Thus there is obtained a clear two-color reproductive copy in which a portion corresponding to the treated portion of the original is colored in brown and other remaining portion corresponding to the untreated portion of the original is colored in dark blue.

Example 8 Multicolor-forming sensitive paper in use for either dry or wet development A solution of the following recipe is prepared:

4-Diazo-2,5-dibutoxy-N-phenylmorpholinel/ZZnCl 15 g Citric acid 30 Diethylene glycol 40 g B-Hydroxynaphthonic acid aminoethyl amine (hydrochloride) 7 g Thiourea 40 g Zinc chloride 30 g Patent Blue 0.l g Water balance Total I liter From the above solution, a photosensitive paper is prepared by conducting the coating and drying in the same manner as in Example 1. The so formed photosensitive paper is piled on an original, a portion of the back surface of which is treated with the ink-like composition prepared in Example A and another portion of the back surface of which is treated with the treating material prepared in Example C. Then the assembly is heated and printed by means of a mercury lamp, followed by development with gaseous ammonia and steam or with an alkaline liquid developer of the following recipe:

Thus there is obtained a clear three-color reproductive copy without any substantial mingling of colors, in which a portion corresponding to the portion of the original treated with the composition of Example A is colored in yellow, a portion corresponding to the portion of the original treated with the composition of Example C is colored in brown and the remaining portion corresponding to the untreated portion of the original is colored in blue.

Example 9 Multicolor-forming film A solution of the following recipe is prepared:

4-diazo-2,5-dibutoxy-N'phenyl morpholine- 1/2 ZnCl Citric acid B-Hydroxynaphtoic acid ethanol amine 7 g. Triacetate resin l g. Oil Blue 0.2 g. Acetone 600 ml. Methanol 400 ml.

The solution is coated on a polyester film by a rod coater and dried at a relatively low temperature (40 50C.) by warm air to form a photosensitive film. The film is placed on an original in which a part of the back surface of an original image is treated with the ink-like agent prepared in Example A and another part of the back surface of the original image is treated with the treating agent prepared in Example B. The assembly is exposed to light by a mercury lamp and heated and printed. The photosensitive film containing a latent image of the diazonium salt is developed with gasified ammonium and steam. Thus, there is obtained a clear three-color reproductive copy without any substantial mringling of colors, in which a portion corresponding to the part treated with the treating material of Example A is colored in yellow, a portion corresponding to the part treated with the treating material of Example B is colored in red, and other portion corresponding to the untreated part of the original is colored in blue.

Comparative Example This example is given to illustrate the relation between the amount of the coupler (b) (having a lower coupling rate than the thermovolatile or thermosublimative coupler (a)) and the effect of preventing the mingling of colors.

Experimental Procedures;

Each of sample solutions having the following composition and containing MA salt and DS acid at a molar ratio, indicated TABLE 1 Sample No. Molar Ratio MA salt DS acid Each of the so formed photosensitive papers is placed on a non-transparent original, a portion of the back surface of which is treated with a treating composition (20 percent solution of resorcinol in ethanol), and the assembly is heat-treated at 70 C. for 4 seconds and subjected to development with gaseous ammonia and steam. Then the degree of distinction in developed colors is examined with respect to each sample. The examination is conducted in accordance with the method of JlS-Z-8722 using a color-difference meter (CS-4A) of Nippon Denshoku Kabushiki Kaisha in the following manner:

The color tones of the portion corresponding to the treated portion of the original and the portion corresponding to the untreated portion of the original are determined by measuring tristimulus values X, Y and Z according to colorimetric system CIE. Then the values of x and y are calculated by the following equations:

x X/X+Y+Z y YIX+Y+Z Based on these values the dominant wavelength (A max) and excitation purity (Pe)are determined from the CIE standard chromaticity diagram, and the effect of preventing the mingling of colors is evaluated from the deviation of the dominant wavelength and the change in excitation purity.

In order to determine the color difference (AE) between the two colored hues, values of L, a and b defined in UCS colorimetric system are measured, and the value of AB is calculated from the following equation:

Results are shown in Table 2.

TAB LE 2 Portion corresponding to untreated portion Portion corresponding tol treated portion Color ditierencc of original of origin between portions corresponding to Dominant Excitation Dominant Excitation treated and wavelength purity (Pe), Sample wavelength purity (Pe), untreated portions Sample No. (A max.), in percent No. (A max), 1111.: percent of orlginul (AB) in Table l is coated by hand on a photosensitive paper sub- NOTES strate:

4Diazo-N,N-dimethylaniline 1. The value of dominant wavelength expressed in minus is the value of complementary dominant wavelength.

2. The unit of 4E is the NBS unit.

The above results are plotted on the CIE chromaticity diagram and shown in FIG. 3.

From the above results the following matters can be seen:

With reference to the color tone in the portion corresponding to the treated portion of the original, if the coupler (b) (DS acid) is used in an amount such that: its molar ratio to the diazonium (c) (MA salt) is l or more (samples t 10), the

dominant wavelength deviates toward the long wavelength area, and at the molar ratio of 2.5 (sample 7) the dominant wavelength comes to be in the range of the complementary dominant wavelength, with the result that the color tone becomes close to the color tone of the portion corresponding to the untreated portion of the original, namely the color tone becomes closer to bluish violet. With reference to excitation purity (Pe), when the amount used of the coupler (b) (DS acid) is increased and the above-mentioned molar ratio is l or more (samples 4 10), the distinctness of color is lowered with the decrease of the value of excitation purity to less than 25 percent, with the result that darkening of color is caused to appear and the color distinction becomes bad.

On the other hand, in case the abovementioned molar ratio is less than 1, namely in case the coupler (b) is used in an amount such as will result in the dominant wavelength of 585 589 mp. and excitation purity of more than 25 percent, the color distinction is excellent and a suitable photosensitive paper is obtainable.

With reference to the portion corresponding to the untreated portion of the original, the increase of the amount used of the coupler (b) (DS acid) results in increase of excitation purity and color distinctness. However, in each sample the excitation purity is above 25 percent and there is no great change in the dominant wavelength except sample 1. Accordingly, from the viewpoint of definite color distinction, samples 1 4 (where the above-mentioned molar ratio is in the range of 0.25 l) are suitable as photosensitive paper. The values of the color difference (AE) between the two colors are considerably different from the values actually found. This is due to the fact that while the value of AE conforms to the actually found value at the center of the chromatocity diagram, in the marginal portion where the color is denser the calculated value of AE is inacurate. Thus these values of the color difference AE are given only for reference.

What we claim is:

1. A process for the diazo-type multicolor reproduction which comprises conducting the steps of (A) exposing imagewise to actinic light a diazo-type photosensitive material having a photosensitive layer containing at least one photosensitive diazonium salt (c) and an azo coupler (b) having a substantially lower rate of coupling with the diazonium salt (c) than that of resorcinol, said azo-coupler being present in the photosensitive layer in an amount of from 0.1 to 1 mole per mole of said diazonium salt (0), and (B) heating at a predetermined portion a layer of at least one thermovolatile or thermosublimative azo coupler (a) which is disposed in face-toface contact with said photosensitive material to produce an azo dye image in the area of the diazotype material contiguous with the heated area of the layer containing azo coupler (a), said steps being performed coincidentally or in the order of (A) to (B) or (B) to (A), and then developing the exposed photosensitive material to produce an azo dye image in the unexposed area of said diazo-type material which is a different hue or color from the azo dye image formed by heating.

2. The process as described in claim 1 wherein the exposed photosensitive material is developed with ammonia and steam or with an aqueous liquid developer containing an alkali.

3. The process as described in claim 1 wherein a transparent or semi-transparent layer, containing at least one thermovolatile or thermosublimative azo coupler (a), is applied to the back surface of a predetermined portion of a transparent or semi-transparent original and then placed on the photosensitive diazo-type material such that the photosensitive layer will be in face-to-face contact with the layer containing azo coupler (a), and both the light exposure and heat transfer of azo coupler (a) are performed when the composite structure is in the above described relationship.

4. The process as described in claim 1 wherein a dyestuff formed from the coupler (b) and the diazonium salt (c) exhibits a hue different from a hue of a dyestuff formed from the thermovolatile or thermosublimative coupler (a) and the diazonium salt (0).

5. The process as described in claim 1 wherein in the photosensitive layer of the photosensitive material the coupler (b) is present in an amount of 0.2 0.9 mole per mole of the diazonium salt (c). 

2. The process as described in claim 1 wherein the exposed photosensitive material is developed with ammonia and steam or with an aqueous liquid developer containing an alkali.
 3. The process as described in claim 1 wherein a transparent or semi-transparent layer, containing at least one thermovolatile or thermosublimative azo coupler (a), is applied to the back surface of a predetermined portion of a transparent or semi-transparent original and then placed on the photosensitive diazo-type material such that the photosensitive layer will be in face-to-face contact with the layer containing azo coupler (a), and both the light exposure and heat transfer of azo coupler (a) are performed when the composite structure is in the above described relationship.
 4. The process as described in claim 1 wherein a dyestuff formed from the coupler (b) and the diazonium salt (c) exhibits a hue different from a hue of a dyestuff formed from the thermovolatile or thermosublimative coupler (a) and the diazonium salt (c).
 5. The process as described in claim 1 wherein in the photosensitive layer of the photosensitive material the coupler (b) is present in an amount of 0.2 - 0.9 mole per mole of the diazonium salt (c). 